Method for coating metal surfaces with a phosphate layer and then with a polymer lubricant layer

Abstract

The invention relates to a method for preparing metal workpieces for cold forming by first applying a phosphate layer and then applying a lubricant layer which has a major content in organic polymer material. The phosphate layer is formed by an aqueous acidic phosphating solution having a major content in calcium, magnesium or manganese and phosphate. The lubricant layer is formed by contacting the phosphated surface with an aqueous lubricant composition which has a content in organic polymer material based on ionomer and optionally also non-ionomer the organic polymer material used predominantly being monomers, oligomers, co-oligomers, polymers or copolymers based on ionomer, acrylic acid/methacrylic acid, epoxide, ethylene, polyamide, propylene, styrene, urethane, the ester or salt thereof. The invention also relates to the corresponding lubricant composition, to the lubricant layer produced thereof and to its use.

The invention claimed is: 
     
       1. A process for the preparation of metallic workpiece comprising:
 forming a phosphate layer on the surface of the metallic workpiece by contacting a surface of the metallic workpiece with an aqueous acidic phosphatizing solution; 
 subsequently applying a lubricant layer coating to the phosphate layer on the surface of the workpiece; 
 wherein the lubricant layer comprises water glass, an amine and a substantial content of organic polymeric material, 
 wherein the aqueous acidic phosphatizing solution comprises phosphate and a content of calcium, magnesium or manganese; and 
 wherein the organic polymeric material comprises an ionomer which comprises a member selected from the group consisting of acrylic acid, methacrylic acid, an epoxide, an ethylene, a polyamide, a propylene, a styrene, and a urethane, or an ester thereof or a salt thereof, 
 wherein at least one of the ionomer and the non-ionomer is at least partly saponified or is an organic salt; 
 wherein the ionomer is an ionomeric copolymer; 
 wherein the lubricant composition further comprises a non-ionic organic polymeric component selected from the group consisting of acrylic acid, methacrylic acid, an amide, an amine, an aramid, an epoxide, an ethylene, an imide, a polyester, a propylene, a styrene and a urethane; 
 wherein the amine is selected from the group consisting of a primary amine, a secondary amine and a tertiary amine; and 
 wherein the lubricant layer comprises less than 0.5 wt. % soap based on the total weight of the lubricant layer. 
 
     
     
       2. A process according to  claim 1 , wherein the phosphatizing solution contains 1 to 200 g/l of compounds of calcium, magnesium or manganese, including the ions thereof, calculated as calcium, magnesium and manganese, no zinc or less than 60 wt. % of the cations as zinc, and 2 to 500 g/l phosphate calculated as PO 4 . 
     
     
       3. A process according to  claim 2 , wherein phosphatizing is carried out electrolytically with an alkaline-earth content of more than 80 wt. % of all cations. 
     
     
       4. A process according to  claim 1 , wherein phosphatizing is carried out electrolytically with an alkaline-earth content of more than 80 wt. % of all cations. 
     
     
       5. A process according to  claim 1 , wherein the amine is a primary amine. 
     
     
       6. A process according to  claim 1 , wherein the amine is a secondary amine. 
     
     
       7. A process for the preparation of a metallic workpiece for cold forming comprising the steps of:
 contacting a metallic workpiece with an aqueous acidic phosphatizing solution comprising phosphate and at least one metal ion selected from the group consisting of calcium, magnesium and manganese to form a phosphate workpiece having phosphate layer on a surface thereof; and 
 subsequently applying a lubricant layer coating to the phosphate layer by contacting the phosphate layer on the surface of the phosphate workpiece with an aqueous lubricant composition; 
 wherein the aqueous lubricant composition comprises 1) an organic polymeric material comprising an ionomer, 2) at least one member selected from the group consisting of a water-soluble oxide, a water-containing oxide, a water-binding oxide and a silicate, and 3) a tertiary amine; 
 wherein the ionomer is an ionomeric copolymer; and 
 wherein the lubricant layer comprises less than 0.5 wt. % soap based on the total weight of the lubricant layer. 
 
     
     
       8. The process according to  claim 7 , wherein the organic polymeric material further comprises an organic non-ionomer. 
     
     
       9. The process according to  claim 8 , wherein the organic non-ionomer is selected from the group consisting of an oligomer, a polymer and a copolymer. 
     
     
       10. The process according to  claim 8 , wherein the organic non-ionomer is based on a member selected from the group consisting of acrylic acid, methacrylic acid, an amide, an amine, an aramid, an epoxide, an ethylene, an imide, a polyester, a propylene, a styrene and a urethane. 
     
     
       11. The process according to  claim 8 , wherein the organic non-ionomer is at least party saponified. 
     
     
       12. The process according to  claim 7 , wherein the ionomer is based on a member selected from the group consisting of acrylic acid, methacrylic acid, an epoxide, an ethylene, a polyamide, a propylene, a styrene, a urethane. 
     
     
       13. The process according to  claim 7 , wherein the organic ionomer is at least partly saponified. 
     
     
       14. The process according to  claim 7 , wherein the organic ionomer is an organic salt. 
     
     
       15. The process according to  claim 7 , wherein the phosphatizing solution contains 1 to 200 g/l of compounds of calcium, magnesium or manganese, including the ions thereof, calculated as calcium, magnesium and manganese, no zinc or less than 60 wt. % of the cations as zinc, and 2 to 500 g/l phosphate calculated as PO 4 . 
     
     
       16. The process according to  claim 15 , wherein phosphatizing is carried out electrolytically with an alkaline-earth content of more than 80 wt. % of all cations.